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Vinyl Window Bucks - A Perfect Fit

One of the fastest growing trends in the ICF industry is the use of vinyl window bucks. Although wood bucks can be used (see the April 2005 issue) the simplicity, ease, and durability of vinyl blockouts are quickly becoming industry standard.

“If they research the technology and choose ICFs, why would anyone put the wood back in?” asks Justin Anderson, founder of Vinyl Technologies.  Vinyl Technologies is by far the largest manufacturer of vinyl window and door bucks, marketed under the V-Buck brand.

Builders like vinyl because they’re a no-hassle, lightweight, easy-to-assemble product that virtually eliminates callbacks.  Customers choose vinyl for the same reasons they choose ICFs.   Both are environmentally friendly, termite and mold proof, contain no hazardous chemicals, and will never rot.  Vinyl will not sustain a burn, and does not contribute fuel to a fire.

Vinyl may cost more than wood, but Anderson claims that when assembly time is considered, the price difference virtually disappears.  “I tell contractors that if labor is a cost, V-Buck costs about the same.”   He says his bucks can be assembled 83 percent quicker than a similar wooden buck; each blockout can be built and braced in five to eight minutes. 

Audrey Anderson, marketing director at Vinyl Technologies, just finished building her own ICF home in New Mexico, and has first-hand experience with assembly.  “The first window took me about 15 minutes,” she admits, “from getting the pieces out to having the buck finished, braced, and ready to go.”  The rest of the windows, though, came together within the expected six-to-seven minute timeframe, she says. 

An added bonus, said Audrey, is that the bucks are light enough she could place them herself, even the larger ones.  At trade shows, the company sometimes holds demonstrations pitting a 12-year-old boy building vinyl bucks against two experienced construction workers building the same thing out of wood.  The boy wins every time.

V-Buck is available in 16 different widths to fit virtually every ICF on the market.  Additionally, round, half round, ellipse, eyebrow, oval and gothic openings are available by special order. General manager Bruce Anderson says, “If there is a window made for the opening, we can match that shape with our block-out. We also fabricate chamfered block-outs for window openings with a wide sill or window seat.”

In addition to Vinyl Technologies, Arxx, ECO-Block, and a handful of others market vinyl bucks.  The ECO-Buck consists of a three-part plank—two side rails and a center piece of variable width, which the builder glues together with PVC cement.  The Arxx product is limited to walls built from the Arxx six-inch block.  Both products are field-cut to fit the window opening, and snapped into place.  Tom Patton, an Arxx technical representative, says the Arxx product can be used for arched windows by cutting the sides of the channel.

At least one company manufactures custom bucks for large commercial projects.  Steve Bollinger, vice-president design and construction division, Drury Hotels, needed window bucks for their prototype 180-room ICF hotel.

“We simply couldn’t find anything out there for what we were trying to do,” he says.

Each window opening is about eight feet tall by four or five feet wide, and the buck needed to incorporate a built-in sill and an opening for air conditioning units beneath each window.  The buck needed to serve as part of the bracing system as well.  Construction would require hundreds of them, with four beginning construction prior to year end.

Royal Building Technologies agreed to manufacture a buck that met those requirements. The first sample bucks arrived at the end of June.  “We won’t be installing the first of those until mid-September,” says Bollinger, “but it should work out great.”

Ease of use is just one reason builders are choosing vinyl.  Whether you choose ICFs for energy-efficiency, durability, or simplicity, vinyl window bucks are a perfect match. 

Installation of Vinyl Window Bucks

Regardless of the size and shape of your openings, the installation procedure for vinyl window bucks is fairly universal. 

1. Place the Order: The first step is figuring out the size, number and shapes of your windows.  The easiest way to do this is to send the buck manufacturer the window take-offs.  They’ll work up the order, figure out how many parts and pieces you need, and ship the order to the jobsite.  You can place the order through your distributor.  Be sure to include any unusual requirements, such as heavy load doors or non-rectangular openings.

Your order will arrive as a bundle of 16-foot-long vinyl planks and several boxes of corners, splices, and other parts.

2. Cut to Size: Cut the vinyl to size using a chop saw with a regular crosscut blade.  Cutting and assembling the window and door bucks off-site will increase jobsite productivity.  If you assemble the bucks off-site, be sure to number them carefully to eliminate the possibility of error.  Remember that the bottom sills of window bucks need a series of 3-inch diameter holes for concrete placement and consolidation. 

If you want to avoid the hassle of measuring and cutting vinyl, you can order your bucks as a kit from Vinyl Technologies.  They’ll even pre-drill the large holes in the bottom buck if you request it.

Some contractors get along without a hole saw by using a chop saw to cut large rectangles in the bottom buck for concrete placement.  “It all depends on how nice you want the job to look,” says Justin Anderson, “either way works.”

3. Assembly: Once the pieces are cut and drilled, the bucks go together fast.  V-Buck, the most common brand, uses corner connectors to fasten the pieces together. Starting with the bottom sill, push the corner connectors into place.  Bucks over eight inches wide need a connector in the center of the plank as well.  Some may need to be tapped into place with a rubber mallet if the fit is tight.

Slide the sides into place next, followed by the top.  If the window is arched, use variable-angle connectors and screw them firmly into place.

4. Bracing: V-Bucks use a simple corner bracing system that squares the buck at the same time it reinforces them.  Lay the buck down in a horizontal position, attach a brace to each corner with screws, then turn the buck over and attach the other four braces.  ECO-Buck uses a similar steel brace, not only to square up to the form, but also to fasten the pieces together. 

Additional bracing is usually installed once the window is placed on the wall.

5. Placement: Once the walls have reached the height of the window, lift the bucks into place.  It should fit snugly over the top of the ICF blocks.  Unlike wood bucks, even large blockouts can be moved by a single worker.  Build the sides up to the required height, then finish the top course, trimming as required. 

Arched bucks are more difficult, since the foam must be cut to match the curvature of the buck. Keep as many ties as possible intact to prevent blowouts.  Anderson claims that cutting blocks is most difficult part of the whole process.  “It’s a matter of the builder knowing his product and the structural limitations of the block and ties.”

Once in place, brace the bucks every 24 inches.  Most builders use Vinyl Technologies’ Power Brace, which is inserted to just a snug fit.  The company has just introduced a “yoke and tie” system for bracing the sides of the bucks. (See New Product Review on p. 18 for more information.)  ECO-Bucks use leftover webs and Zip Ties to secure the form and the buck. 

Limitations: Anderson said that sometimes builders forget that the buck is not a finished product, or the simplicity of the buck leads them to forget basic physics. “You do have to respect the material,” he notes.  “The heat of the concrete curing, combined with the weight of the material, will bow the vinyl if not installed and braced properly.” Use scrap wood to distribute the strength of the bracing across the entire width of the buck. 

Anderson offers one more word of caution.

 “Our window bucks are a little flexible,” he says.  “That allows for a field fit.”  It also allows for bucks to shift slightly if not installed properly.  “I always tell builders to cut a piece of OSB or plywood the size of the window and make sure that it fits into the buck before the pour.”

When installed properly, however, it takes ICF construction to a whole new level.  “It definitely increases street appeal,” Audrey Anderson says.   “People drive by and see the project and think ‘what a beautiful white building.’”

Advantages of Vinyl Bucks

  • Easy-to-assemble
  • Lightweight
  • Handles complex openings easily
  • Termite-proof
  • Mold-proof
  • Rot-proof
  • Environmentally friendly
  • Minimal waste
  • Increases street appeal
  • Will not warp or twist
  • Will not react to concrete
  • Will not leak.
  • Will not release hazardous chemicals
  • Not a fuel source for fire
  • Avoids fluctuating lumber costs


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